Chousin - trio who created the universe
Lord of nightmare
Locke - immortal and nearly omnipotent
Demonbane - Demonbane is a mech which
- has infinite speed, power, and everything else
- can destroy multiverses
- time-space control
- if it dies, it goes back 5 sec.
- can survive from not existing. so, it can't be removed from existence

Tenchi Masaki - omnipotent. Even if you argue that he isn't, he fought in space without oxygen (I believe) and escaped black hole and traveled far faster than light.

The people I mentioned are far far far stronger than Goku and Alucard. Not even death note can kill some of them.

wow Demonbane is the only mech that can go toe to toe with his kickassness Ideon;

Lord of Nightmares is Slayers? whats Locke? the politician? hes that good?

http://kanzaka.wikia.com/wiki/Lord_of_Nightmares Yes, slayers
http://en.wikipedia.org/wiki/Locke_the_Superman I haven't watched it though. I am planning to watch that. So, I don't know what he exactly is except that he is an esper. So, I don't know if he's politician, but he must be good.

Light from Death Note
If he knows your face and name he can just kill you
thats pretty overpowerd

Well, he did get defeated, shot multible times, stopped from killing near, and had one of the most humiliating death scenes of any anime series, so he cannot be all that powerful.

Someone like Kazuma Yagami, who basically has the power of a wind god, or Madara Uchiha, who basically couldn't even be killed by what would be the most powerful ninja in existence, would be considered just a bit overpowered. I mean, no one could even lay a scratch on them.

Among these three monsters I think Takumi stands above some others as a real monster due to the fact as a "special" gigalomaniac he is able to materialize his delusions into reality(real-boot) without a conduit(Di-sword). Because he is able to make his imaginations come true, he can warp reality's possibilities. If abused it can certainly turn into a lethal silent weapon of mass destruction...

Owns every single physical noble phantasm that has ever existed, plus Ea, a sword which unleashes a maelstrom that at full power is absolutely impossible to block or avoid. If it weren't for his ego, he would have won both Holy Grail Wars in about five seconds.

Pretty sure that Archer kicks his ass with relative ease though since his noble phantasm can copy any other attack or ability it pleases on top of being more powerful.
Unlimited blade works!

(btw I say archer since for anyone who has not played the VN or seen unlimited blade works the true identity is spoilerific.)

Divine constructs, such as Ea and Excalibur, are unable to be replicated, though there may be degraded Noble Phantasms with similar abilities stored with the Reality Marble.[1] The construction of weapons is also limited to materials found upon the planet in the present era, so weapons like Ea, which is constructed from substances not found in the world, cannot be analyzed or reproduced.

Divine constructs, such as Ea and Excalibur, are unable to be replicated, though there may be degraded Noble Phantasms with similar abilities stored with the Reality Marble.[1] The construction of weapons is also limited to materials found upon the planet in the present era, so weapons like Ea, which is constructed from substances not found in the world, cannot be analyzed or reproduced.

Exactly, Ea is unable to be replicated by Archer's reality marble. Since that is Gilgamesh's most powerful
weapon, and also as we see in Fate/Zero capable of completely destroying a reality marble, Gilgamesh would be the most powerful. However, Gilgamesh is such an elitist he probably wouldn't want to use it on a "faker" like Archer unless completely backed into a corner, so it is possible that Archer could win the same way Shirou did, but only because of Gilgamesh's ego.